feat: add C implementation for `stats/base/dists/poisson/mgf` #21434

Job	Run time
Add initial reaction	6s
Update copyright header years	0s
Print a list of available slash commands	0s
Merge changes from develop branch into this PR / Merge Develop into PR Branch	1m 41s
Post a comment with make command instructions	0s
Check for required files	0s
Auto-fix lint errors	0s
Rebase this PR on top of develop branch	0s
Remove in-progress label	3s
	1m 50s

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